The current commercial specifications for digital audio, compact discs ("CD-DA") i.e., the format for storing and playing high fidelity audio tracks, and compact disc-read only memory ("CD-ROM"), i.e., the format for storing and retrieving data intended to be accessed by general purpose personal computers, have been co-developed by Philips N.V. and Sony Corporation. These specifications are commonly referred to as the Red Book (for compact disc digital audio) and the Yellow Book (for CD-ROM) each of which is a technical specification created by Philips N.V. and Sony Corporation entitled "Compact Disc Digital Audio System Description" and "Compact Disc-Read Only Memory System Description," respectively. A commercial specification for CD-DA is also published by the international Electrotechnical Commission, entitled IEC Publication 908 "Compact disc digital audio system."
In addition to the information structure and layout for CD-ROM, the CD-ROM outlines the specification for placing CD-DA audio tracks on a CD-ROM disc. This specification is commonly called the Multimode format. See FIGS. 1 and 5.
However, for reasons discussed below, the Multimode format has not been fully accepted by the audio industry as a suitable distribution medium for audio compact discs that also contain CD-ROM material. With this in mind, a set of special methodologies have been developed which define alternate methods for placing CD-ROM and CD-DA audio tracks on the same disc. These methodologies are referred to herein as the invented Multimode methodologies.
The Multimode format is not fully accepted by the audio industry for the following reasons:
(a) According to the Multimode format, the CD-ROM volume must be placed in Track 1, Index 1 while the CD-DA audio selections are placed in tracks 2, 3, . . . , N as shown in FIG. 1. For this case, Track 1, Index 0 must be 2 seconds long and usually consists of block structured CD-ROM Mode 1 data with the user data field set to 2048 bytes of binary zeroes. (On a pure CD-DA disc, Track 1, Index 0 is 2-3 seconds long and contains digital silence.) Standard compact disc audio players will attempt to "play" the CD-ROM information in Track 1, Index 1. Therefore, unless notified to use the "NEXT TRACK" entry on the player's control panel or remote, the end-user will experience a very long pause before the first CD-DA audio track is heard. The length of this pause will be equal to the "real-time" length of the CD-ROM track. PA1 (b) In relation to the problem listed in (a), a few first generation compact disc audio players do not possess the control circuitry required to detect and then mute CD-ROM tracks. In these instances, the compact disc audio player attempts to convert the CD-ROM information into an analog signal. The resulting signal is passed through the speaker system as full volume static. This can be very damaging to the speakers as well as to the listener's hearing.